The present invention relates to a filling apparatus for, a filling system for and a method of introducing into a container a suspension or solution of a substance, in particular a pharmaceutical substance, in a propellant under pressure. Most particularly, the present invention relates to a filling head included in a line in which a propellant under pressure containing a substance in a suspension or solution is circulated, with the filling head being brought into and out of communication with containers to be filled.
Containers for holding a suspension or solution of a pharmaceutical substance in a propellant under pressure are well known. One such known container comprises a body which defines a storage chamber, a valve stem which extends from a head of the body and a metering chamber which is selectively communicatable by the valve stem with the atmosphere and the storage chamber; the valve stem providing, via an L-shaped conduit which extends between the free end and the side wall thereof, the outlet of the container through which metered doses of propellant containing pharmaceutical substance are delivered. The valve stem is axially displaceable between a first, extended position in which the metering chamber, and hence the container, is closed to the atmosphere since the L-shaped conduit is disposed wholly outside the metering chamber, and a second, depressed position, in which the metering chamber is in communication with the outlet provided by the L-shaped conduit in the valve stem and through which a metered dose of propellant containing pharmaceutical substance is delivered. The container is filled with the valve stem in the depressed position, with the propellant containing pharmaceutical substance being forced downwardly through the L-shaped conduit in the valve stem, through the metering chamber and into the storage chamber defined by the body of the container.
EP-A-0419261 discloses a filling system for introducing into a container a suspension or solution of a pharmaceutical substance in a propellant under pressure, which filling system includes a filling apparatus that prevents the escape of pharmaceutical substance into the atmosphere. In this filling system the filling apparatus is configured to be flushed by a volume of high pressure propellant while still in fluid communication with the container so that the propellant under pressure containing pharmaceutical substance which is remaining in the filling apparatus after filling the container with the same is flushed through into the container prior to withdrawal of the filling apparatus from the container. This configuration does, however, require additional propellant to be introduced into the container to achieve the flush. Moreover, following the flushing action, propellant under pressure present in the valve stem can escape to the atmosphere.
The present invention in at least one preferred aspect aims to provide an improved filling apparatus which at least partially overcomes the above-mentioned problems.
The present invention also aims to provide a method and filling system which are configured to fill a container without requiring the release of propellant alone or propellant containing pharmaceutical substance directly to the atmosphere.
The present invention provides a filling apparatus for introducing into a container a suspension or solution of a substance, in particular a pharmaceutical substance, in a propellant under pressure, comprising: a main body including a passageway having an inlet opening and first and second outlet openings, the first outlet opening communicating, in use, with a valve stem extending from a head of a body of a container; a fill actuator in communication with the inlet opening of the passageway comprising a filling valve assembly for selectively introducing propellant under pressure containing a substance in a suspension or solution into the passageway; an exhaust actuator in communication with the second outlet opening of the passageway comprising an exhaust valve assembly for selectively exhausting propellant under pressure containing substance from the passageway and including at least one exhaust gas conduit having an outlet configured so as, in use, to provide a flow of exhaust gas substantially aligned with a flow of propellant containing substance from the second outlet opening of the passageway; and a container-engaging body for receiving, in use, the head of the body of the container which includes the valve stem.
Preferably, the exhaust actuator includes a plurality of first exhaust gas conduits, the respective outlet openings of which define an array surrounding the second outlet opening of the passageway.
More preferably, the outlet openings of the first exhaust gas conduits are disposed downstream, with respect to the direction of flow, of the second outlet opening of the passageway.
More preferably, the array of outlet openings of the first exhaust gas conduits define a circular array.
Preferably, the exhaust actuator includes a first chamber with which the first exhaust gas conduits commonly communicate and a conduit in communication with the first chamber through which exhaust gas is delivered.
In a preferred embodiment the exhaust actuator includes a plurality of second exhaust gas conduits, the respective outlet openings of which are downstream, with respect to the direction of flow, of the outlet openings of the first exhaust gas conduits and define an array surrounding the second outlet opening of the passageway.
Preferably, the array of outlet openings of the second exhaust gas conduits define a circular array.
Preferably, the exhaust actuator includes a second chamber with which the second exhaust gas conduits commonly communicate and a conduit in communication with the second chamber through which exhaust gas is delivered.
Preferably, the exhaust valve assembly includes an exhaust valve body which is configured selectively to be seated on or unseated from a valve seat disposed at the second outlet opening of the passageway and a substantially annular chamber which surrounds the exhaust valve body through which, in use, flows propellant containing substance and exhaust gas when the exhaust valve body is unseated from the valve seat.
More preferably, the annular chamber is conical in shape, increasing in diameter from the second outlet opening of the passageway.
The present invention also extends to a filling system for introducing into a container a suspension or solution of a substance, in particular a pharmaceutical substance, in a propellant under pressure incorporating the above-described filling apparatus.
The present invention further provides a method of introducing into a container a suspension or solution of a substance, in particular a pharmaceutical substance, in a propellant under pressure, comprising the steps of: providing a container comprising a body defining a storage chamber and a valve stem extending from the body; communicating the valve stem of the container with a first outlet opening of a passageway in a main body of a filling apparatus, the filling apparatus comprising a fill actuator comprising a filling valve assembly for selectively introducing into an inlet opening of the passageway propellant under pressure containing a substance in a suspension or solution and an exhaust actuator comprising an exhaust valve assembly for selectively exhausting propellant under pressure containing substance from a second outlet opening of the passageway and including at least one exhaust gas conduit having an outlet configured so as, in use, to provide a flow of exhaust gas substantially aligned with a flow of propellant containing substance from the second outlet opening of the passageway; opening the filling valve assembly thereby to fill the storage chamber of the container with propellant under pressure containing substance in a suspension or solution; closing the filling valve assembly; providing exhaust gas through the at least one exhaust gas conduit; and opening the exhaust valve assembly to enable propellant under pressure containing substance in the passageway and the valve stem of the container to exhaust, whereby the exhausted propellant containing substance is entrained in the exhaust gas.
Preferably, the exhaust actuator includes a plurality of first exhaust gas conduits, the respective outlet openings of which define an array surrounding the second outlet opening of the passageway.
More preferably, the outlet openings of the first exhaust gas conduits are disposed downstream, with respect to the direction of flow, of the second outlet opening of the passageway.
More preferably, the array of outlet openings of the first exhaust gas conduits define a circular array.
Preferably, the exhaust actuator includes a first chamber with which the first exhaust gas conduits commonly communicate and a conduit in communication with the first chamber through which exhaust gas is delivered.
In a preferred embodiment the exhaust actuator includes a plurality of second exhaust gas conduits, the respective outlet openings of which are downstream, with respect to the direction of flow, of the outlet openings of the first exhaust gas conduits and define an array surrounding the second outlet opening of the passageway.
Preferably, the array of outlet openings of the second exhaust gas conduits define a circular array.
Preferably, the exhaust actuator includes a second chamber with which the second exhaust gas conduits commonly communicate and a conduit in communication with the second chamber through which exhaust gas is delivered.
Preferably, the exhaust valve assembly includes an exhaust valve body which is configured selectively to be seated on or unseated from a valve seat disposed at the second outlet opening of the passageway and a substantially annular chamber which surrounds the exhaust valve body through which, in use, flows propellant containing substance and exhaust gas when the exhaust valve body is unseated from the valve seat.
More preferably, the annular chamber is conical in shape, increasing in diameter from the second outlet opening of the passageway.
Preferably, the exhaust gas is heated to a temperature of at least about 35xc2x0 C.
Preferably, the ratio of the mass flow rate of the exhaust gas to the exhausted propellant containing substance is at least 10:1.
Preferably, the exhaust gas has a mass flow rate of from 0.1 to 10 grams/second.
Preferably, the exhaust gas comprises pressurised air.